1. Field of the Invention
This invention relates to a method of reusing a slurry in a ground improving method, wherein a hardening agent is injected into the ground, and wherein muddy water; i.e., slurry which is discharged upon working thereof is regenerated and again used as an injection material; namely, a hardening agent.
2. Discussion of the Relevant Art
In the above-discussed method of reusing slurry, with respect to the hardening agent which is injected into the ground, the hardening agent of a quantity which is equal to or larger than the amount corresponding to the volume of a hole dug in the ground and gaps in the ground are discharged as slurry onto the ground. The slurry which is discharged onto the ground is at present abandoned as industrial waste. A discharge amount of the slurry differs depending on the kind of the ground improving method being employed. In addition, the content of sediment in the discharged slurry also differs depending on the working condition and working method being employed.
However, the process for abandoning the slurry as industrial waste causes an increase in processing cost. In addition, a present situation wherein the decrease in the number of construction for processing facilities of the industrial wastes facilitates an increase in processing cost. Therefore, there is a strong demand for reusing the slurry for the hardening agent contained in the slurry.
When reusing the slurry, a technique for measuring a quantity of hardening agent contained in the discharged slurry is inevitable. Techniques for measuring an amount of hardening agent contained in the slurry includes a calcium analysis method, a pH measuring method and a boron tracer.
The calcium analysis method is a method whereby after an amount of calcium in a consolidation sample is measured, a calcium element component of the hardening agent is counted back and a content of the hardening agent is obtained from the calcium element component. However, the above method has a problem in that a fairly large amount of labor is expended to measure the content.
The pH measuring method estimates a range of an amount of hardening agent on the basis of the numerical value obtained from the working processes (i.e., actual results) from an alkalinity (pH) which the hardening agent liquates and physical properties (i.e., specific gravity or the like) of the discharged slurry. However, according to this method, since the numerical values obtained from the actual results are used, there is a problem in that the latest information cannot be obtained on every ground.
The boron tracer method is a method whereby by using the principle in which boron atoms absorb the neutrons, boron atoms are mixed into the hardening agent so as to keep a concentration of boron atoms constant, the number of boron atoms is measured, and thereby, obtaining a quantity of hardening agent. This method has an advantage in that the quantitative measurement of the hardening agent can be performed. However, there is a problem in that a radioactive isotope (RI) must be used upon measurement.
The present invention is made in consideration of the problems of the conventional techniques mentioned above, and it is an object of this invention to provide a method for reusing a slurry in the ground, wherein a quantity of the hardening agent contained in a discharged slurry can be accurately and suitably measured and the demand to reuse the slurry (i.e., the hardening agent contained in the slurry) can be satisfied.